Coke quenching method and apparatus with cool coke recycle



Aug. 22, 1961 v. MANsFlELD 2,997,427

COKE QUENCHING METHOD AND APPARATUS WITH COOL COKE RECYCLE Filed Nov. 2, 1959 l f: l, l l I ATTORNEY United States Pate-nt Q z' suv-1,421` coxn QUENCHING nrarnon AND APPARATUS WITH cooL coKE REcYcLE Vaughn Mansfield, 5340 Delmar Blvd., sf. Louis, M0.

Filed Nov. 2, 1959, Ser. No. 850,389

11 Claims. (Cl. 20237) a This invention relates to a combined coke cooler and air preheater for a coking stoker. More particularly, the invention concerns a method and apparatus wherein a portion of cooled coke is recycled into a stream of hot coke' to reduce the temperature of the stream below its ignition temperature, whereby air may be circulated through the coke stream so as to preheat the air while cooling the coke. The invention is particularly adapted for use with coklng stokers of th'ety-pe shown fin-the copending applications of Mansfield, .entitled Method and Apparatus for Continuous Coke Production While Extracting Low Temperature Volatiles, Serial No. 820,213, tiled June l5, 1959, iand Method and Apparatus for Producing Coke and'. Heat Whilev Extracting L'ow Temperature Vo-latiles, Serial No. 850,388, iled'November 2, 11959. In order to appreciate the function of' the invention, it is suiiicient tounderstand that, in coking stokers of the type abovereferred to, the coal is fed onto a travelling gratestoker to 'form a bed which passes slowly through an oven. Preheated fuel gas is fed upwardly through the bed so. as to raise the bed temperature sulciently to drive offmost of the volatile matter from the coal, and limited exi-- dation in the bed occurs'. Aslthe nearly completely cari bonized hot coal bed passes off the output end of the` Stoker, suihcient residual 'Qvola'tilesj remain in the coke so'that, if air were then used to cool it, the xed carbon would ignite, and if water were used to quench it, water gas would be Vcreated `and excessive amounts of coke would be consumed.

According to `this invention, the nearly devolatilizedf hot coke discharged from the output end ofthe coking oven is rst caught and maintained in a column retort,i

or devolatilizing cooker. As .the coke column progresses slowly downwardly in the cooker, the latent heat of the 2,997,427 Patented Aug. 22, 1961 ICC 2 range of l,650 F. to 1,800 F. for a suflicient length of time, will be driven off.

The hot coke falling through discharge opening 6 is caught and maintained in a column, as indicated at 8, in a devolatilizing cooker 10 having refractory walls 12j.- The column 8 of hot coke is permitted to move slowly downwardly in cooker 10 and it remains in the column suiiciently long for the latent heat in the coke -to drive' olf virtually all of the residual volatiles which rise, 'as indicated by the arrow 14, and drift back into a coking oven, in which they are consumed. As the stack of hot coke moves slowly downwardly in cooker 12, heat is lost so that, by reaching the outlet 16 of the cooker, the teme perature of the coke will be assumed to be about 1,6505' F. AVirtually no air is permitted to flow upwardly througlr coke column y8, the coke being discharged from cooker 10 by'` a cast iron drum feeder 18, or a cast iron screw:A

feeder, which passes -the coke outwardly beneath the;

gate 20. It will be understood that the coke emerging from outlet 16, vwhile somewhat cooler than it was upon leaving the coking oven, is nevertheless suflciently hot so that it would imm ediately burn if air were supplied to 5 it for cooling. v

discharged through an outlet 24 onto a downwardly in? i' clined vibrating cooler deck 26, on which the coke i coke drives olf virtually all of the residual volatiles, which.v

pass back into the coking oven. While part of the latent were exposed to air,` it vwould instantly ignite and burn to'ash. The object of the method and apparatusv oflthis invention is to blend in, with the hot coke dis-l charged fromV thecooker, sufficient cool coke so as toreduce the temperature of the aggregate blend below its ignition temperature. YIt is intended that air be then circulated through the partly cooled non-ignitable coke so as to cool it further, Aand to pre-heat the air, the preheated air then being utilized in the coking oven.

These-and'other objects will be apparent in the following specification anddrawing, in. which the 4sole figure shows the parts vin .diagrammatic crossasection.

Referring now to the drawing, in whichlike reference numerals denote similar elements, from the output end 12, of a coking oven, hotcoke 4, falls from the end of a travelling grate Stoker 5 through a discharge opening 6. .For purposes of understanding the subject invention, it is suicient to note that the .coke`4 khas been nearly completely carbonized in ,an atmosphere with suiciently.

spread to form a layer by a conventional spreader l27.3 Vibrating cooler deck 26 has a solid upper section 28' a'nd a lower perforate screen section 30, both sections; being' providedwith suitable supports diagrammatically indicated at 32 and a conventional vibrating mechanisml 34.- An enclosure 36 confines the region above the solid' section 28 of the vibrating cooler deck. A' vent 38 leads'i upwardly from enclosure 36 into the upper portion-of retort 22- and a second vent 39 leads from the top o'f' retort 2 2 back into the outlet end of coking oven y2. Air' Ileaking into enclosure 36, in such small quantities that it will'not result in significant burning of the hot coke# sweeps 'oi dust from the coke evolved during the agitation o'fthe coke -asit' moves along the solid deck section `28 and, previously, as it falls into retort 22. The dustre-l turned' to the coking oven via vents 3S and 29 is-con sumed in the coking oven. As the coke passes along the.- solid section of the shaking conveyor, it is rst spread' to form a thin layer, and the thorough Iand intimate intermingling of the hot and cool coke, started when the'l two were blended in the retort, is completed so thatno-v excessively hot spots or incandescence exist in the blend as it passes onto the screen section of the shakingf conveyor.Y

A hood 40 is Idisposed over the Lscreen section 30 ofvibr'ator cooling deck 26 and an air conduit 42 leads! from below screen section 30. Floating air seals 44a and"- 44b are provided beneath the -lower edges of hood 40 at the upper and lower ends of the 4screen section 30. Ordi-1` narily, and but for the subject invention, the temperaturei of lthe coke bed, as it passes onto screen section 30 of the? vibrating cooler deck, would still be Well `above the igni; l tion point so that itwould burn if attempt were made tof cool it by air circulating through screen section 30. The',I coke bed, however, is cooled -and ignition is prevented asf follows.

As the coke drops olf the lower end of the screen section 30 of vibrating cooler deck 26, it falls onto a gather-: ing conveyor 45 which delivers it to a hopper 46. Part of the coke is discharged from hopper 46 to a loading conveyor as indicated by the arrow 48. However, another portion of the coke vfrom hopper 46 is recycled according: to the demands of a temperature sensing device 50 in ren tort i22. YThe device 50 senses the temperatures of the coke mass near the bottom of retort 22 and, by means of a connection indicated by the broken line 52, provides a signal which controls a mechanical actuating unit 54 wh-ich, in turn, moves an apportioner 56 in hopper ,46. Apportioner 56 splits the stream of cool coke falling through hopper 46 into two portions which vary in relative amounts, depending on the 4demands of temperature sensing device 50. Part of the cool coke from hopper 46 is returned via an outlet S8 in hopper 46, a recycle conveyor diagrammatically indicated at 60 and arrecycle input 62 into the top of retort 22, from which it drops and mingles with the mass of hot coke discharged into the retort by drum feeder 18 from `cooker 10. If the temperature sensed by device 50, which may be a thermocouple or other conventional temperature sensing` unit, is higher than a predetermined degree, i.e., 600 F., me'- chanical actuating uni-t '54 is thereby controlled so as to swing apportioner 56 so as to increase the amount ofcoke recycled via conveyor 60 back into retort` 22. If the temperature sensed by device S is below the given dcgree, apportioner 56 will be actuated by unit 54 so as to decrease the amount of cool coke recycled by conveyor 60, and increase the amount discharged on to the loading conveyor, The desired temperature of the coke, 'as sensed by device 50, emerging from retort outlet 24 onto vibrating cooler deck 26 should be such that the coke bed emerging from the lower end of enclosure 36 is below the point at which the coke will ignite when the air ilows through it. The highest permissible temperature of the coke bed, as the latter leaves the solid section 28 of the vibrator cooler deck, is estimated to be 600 F. Cool air from a supply 64 is fed downwardly through hood 40, as indicated by arrows 66, and downwardly through the coke bed on screen section 30, through the screen section, and exhausted via conduit 42 as indicated by arrows 68. The air, having extracted heat from the coke bed, is preheated and used for various purposes in the coking oven. By the time the coke on screen section 30 reaches floating air seal `44b, it will have been cooled to a temperature of approximately 200 F. For starting the process, a supply of cool coke should be retained for recycling, or the coke in retort 22 can be water or steam quenched, on a Itemporary basis, until a starting supply of cool coke is obtained.

lf desired, in order to prevent plugging of screen deck 30 and to handle the siftings through the screen deck,- the direction yof air ilow may be reversed in the direction of broken arrows 66', 68 so that air is pulled upwardly through the screen deck. In that event, a solid deck 30a, diagrammatically shown in broken lines, would be spaced below the screen deck so as to catch the siftings; and cooling air would be drawn in from the ends from vents 70a and 70b, and also through side vents, not shown. This mode of air cooling would also have certain advantages in reducing the amount of dust escaping through -air seal 44b.

The temperatures estimated for the various steps in the process may vary according to the temperature of the Coke upon leaving the stoker, the amount of heatl lost in the cooker, the ignition temperature of the coke, and the temperature and amount of coke recycled into the retort. In interpreting the claims, it will be understood that the starting temperature of the coke, in entering the quenching apparatus, is substantially above the degree at which it' would ignite if exposed to substantial amounts of air; .the coke, as it starts along the screen section of the shaking conveyor, is below the temperature at which ity will ig- :liteV when suliicient air is blown through to cool it; and, upon leaving the hopper at the end of the process', the coke is not only su'iciently cool that it may be handled but, also, that the recycled cool coke will cool the hot coke to below its ignition temperature. It will be understood also that the volume and size of the cooker, retort and shaking conveyor, and rates of ilow through the cooker, retort and along jt'h'e shaking conveyor are suinciently large to handle the output of the coking oven and (for the retort and shaking conveyor) the output of the coking oven plus l the recycled coolcoke. The rate of flow through the shaking'-c'onveyor maybe changed by altering the tilt of the conveyor `or by changing the shaking rate. A* n A According to presentestimates, itv'will be necessary to recycle about 35,437 lbs. of cool coke, at 200 F. per each 13,500 lbs. of hot coke falling into retort 22 so that the temperature of the resultant blend leaving the retort will be about 600 F. L

The invention isnot limited to the details of the apparatus and the method disclosedand described hereinbefore, but is intended to cover all substiutions, modicaf tions and equivalents within .the scope of the following claims.

l. The method of yquenching hot -coke from a tempera' ature substantially above an ignition point at which the coke would readily, burnif exposed to air in substantial quantities, to an andai-'process temperature greatly below the point at which the coke would ignite `if exposed to air in quantities sufficient to coolit; said method com# prising; coniining the hot coke ina non-oxidizing atmosphere, reducing the temperature of thel confined coke to slightly below the ignition point by the steps including blending cool coke with the hot .coke and intermingling the hot coke with the cool in v,said non-oxidizing atmosphere so as tov transfer heat from .the hot coke tothe coolucoke until the temperature of the resultant blend is below the ignition point thereof inain and subsequently air-cooling the blended coke to said end-of-process temi perature'. v i

2. The method of vquenching hot cokefrom a temperature substantially above an ignition point at'which the coke would readily` burn if exposed to air in substantial quantities, to an end-of-process temperature greatly below the ignition point, said method comprising; coniining the hot coke in a non-oxidizing atmosphere, reducing the temperature of the conlined coke to` slightly below the ignition point by the steps including recycling cool coke and blending the same withthe hot coke and intermingling the hot coke with the cooly iu said non-oxidizing atmosphere so as to transfer heat from the hot coke to the cool coke until the temperaturev of the resultant blend is below the ignition pointthereof in air, and subsequently air-cooling the blended coke to saidY end-of-process' temperature. v

3. Apparatus for quenchingv hot coke; comprising a substantially air-tight receiver having' an input and an output for receiving and confining the hot` coke in' a subu stantially oxygen-free atmosphere-conveyor means having an input for receiving coke from the receiver output and for transporting the same from" the receiver, means for spreading the coke on the conveyor-to form arela'tively thin layer thereon, means for passing cool air through the layer of coke intransitl on the conveyor, and means for recyclingv a'portionof theair-cooled coke from thev conveyor back to the receiver',l whereby to transfer heat from the hot coke in the receiver to the recycled cool coke.

4. Apparatus for quenching hot coke comprising' cooker means for receivigh'ot coke andmaintaining the same in a mass slowly moving therethrough, substantially air-tight receiver meansI for receiving and holding the coke from said cooker,- saidreceiver having means for discharging coke therefrom,-a shaking conveyor hav-v ingY an input portion comprising an imperforate, substantially air-tight deck sectionfor receiving coke from said discharge means, meansA forming a substantially air-tight Yhood over thev imperforate deck` section, and an outputv portion comprising' aperfoate .deck section for receiving* coke from said imperforate sectiommeans for circulating a cooling medium through the coke on said second section whereby to cool the coke thereon, and means for recycling a portion of the fluid-cooled coke from said second section back into said receiver.

5. Apparatus for quenching hot coke comprising cooker means for receiving hot coke and maintaining the same in a mass slowly moving therethrough, substantially air-tight receiver means for receiving and holding the coke from said cooker, said receiver having means for discharging coke therefrom, a shaking conveyor having an input portion comprising an imperforate, substantially air-tight deck section for receiving coke from said discharge means, means forming a substantially air-tight hood over the imperforate deck section, and an output portion comprising a perforate deck section for receiving coke from said imperforate section, means for circulating a cooling medium through the coke on said perforate section whereby to cool the coke thereon, means for recycling a portion of the fluid-cooled coke from said second section back into said receiver to `form a blend with the coke received from the cooker, means in the receiver adjacent the discharge means thereof for sensing the temperature of the blend prior to the reception thereof on the second section of the conveyor, and means for controlling the amount of recycle coke in accordance with the sensed temperature of the blend.

6. Apparatus for quenching hot coke, comprising a substantially air-tight retort for receiving hot coke, said retort having a coke outlet, a downwardly inclined shaking conveyor having a solid upper deck section for receiving coke on its upper side from the retort outlet and a perforate lower deck section, means conning the upper side of said solid deck section in a substantially air-free atmosphere, means for circulating cooling air through the perforate lower deck section and the coke thereon, and means `for recycling a portion of the cooled coke from said perforate deck section back into said retort.

7. Apparatus for quenching hot coke, comprising a substantially air-tight retort for receiving hot coke, said retort having a coke outlet, a downwardly inclined shaking conveyor having a solid upper deck section for receiving coke on its upper side from the retort outlet and a perforate lower deck section, means confining the upper side of said solid deck section in a substantially air-free atmosphere, means for circulating cooling air through the perforate lower deck section and the coke thereon, means for recycling a portion of the cooled coke back into said retort and for blending the same with the hot coke therein, temperature sensing means in said retort adjacent the coke outlet, and means for controlling the amount of recycled coke in accordance with the sensed temperature of the blend.

8. Apparatus for quenching hot coke, comprising a cooker receptacle for maintaining the hot coke in a ver- 6 tical column, said cooker receptacle having an input at its upper end and a substantially air-tight dispenser at its lower end, a substantially air-tight retort for receiving coke from said dispenser, said lretort; having a coke outlet, ya downwardly inclined shaking conveyor having a solid upper deck section for receiving coke on its upper side from the retort outlet and a perforate lower deck Section, means confining the upper side of said solid deck section in a substantially air-free atmosphere, means for circulating cooling lair through the perforate lower deck section and the coke thereon, means for receiving the cooled coke from said pcrforate deck section, and means for recycling a portion of the cooled coke back into said retort.

9. Apparatus for quenching hot coke derived from a coking oven comprising a cooker receptacle ffor receiving and maintaining the hot coke derived from said oven in a vertical column, said cooker receptacle having an input at -its upper end communicating with the oven and a substantially air-tight dispenser at its lower end, a substantially air-tight retort for receiving coke from said dispenser, said retort having a coke outlet, a downwardly inclined shaking conveyor having a solid upper deck section for receiving coke on `its upper side from the retort outlet and a perforated lower deck section, means conning the upper side of said solid deck section in a substantially air-free atmosphere, means for circulating cooling air through the perforate lower deck section and the coke thereon, means for receiving the cooled coke from said perforate deck portion, and means for recycling a portion of the cooled coke back into said retort whereby to blend the same with the hot coke #from said dispenser.

10. The combination claimed in claim 9, means in said retort -for sensing the temperature of the blend, and means for controlling the amount of coke recycled in accordance with the sensed temperature of the blend.

11. The combination claimed in claim 9, means for venting dust from said conveyor, and means for feeding the vented dust back into said oven.

References Cited in the tile of this patent UNITED STATES PATENTS 972,352 Ely et al. Oct. 11, 1910 1,593,698 Illingworth July 27, 1926 2,090,363 Wendeborn Aug. 17, 1937 2,467,519 Borghesan Apr. 19, 1949 2,772,225 Bergstrom et `al Nov. 27, 1956 2,895,231 Sylvcst July 21, 1959 OTHER REFERENCES 1,032,697 Germany June 19, 1958 

1. THE METHOD OF QUENCHING HOT COKE FROM A TEMPERATURE SUBSTANTIALLY ABOVE AN IGNITION POINT AT WHICH THE COKE WOULD READILY BURN IF EXPOSED TO AIR IN SUBSTANTIAL QUANTITIES, TO AN END-OF-PROCESS TEMPERATURE GREATLY BELOW THE POINT AT WHICH THE COKE WOULD IGNITE IF EXPOSED TO AIR IN QUANTITIES SUFFICIENT TO COOL IT, SAID METHOD COMPRISING; CONFINING THE HOT COKE IN A NON-OXIDIZING ATMOSPHERE, REDUCING THE TEMPERATURE OF THE CONFINED COKE TO SLIGHTLY BELOW THE IGNITION POINT BY THE STEPS INCLUDING BLENDING COOL COKE WITH THE HOT COKE AND INTERMINGLING THE HOT COKE WITH THE COOL IN SAID NON-OXIDIZING ATMOSPHERE SO AS TO TRANSFER HEAT FROM THE HOT COKE TO THE COOL COKE UNTIL THE TEMPERATURE OF THE RESULTANT BLEND IS BELOW THE IGNITION POINT THEREOF IN AIR, AND SUBSEQUENTLY AIR-COOLING THE BLENDED COKE TO SAID END-OF-PROCESS TEMPERATURE. 